The invention concerns a regulator loop having temperature compensated diode detector to detect an RF signal and a radio telephone having such a regulator loop having temperature compensated diode detector in its transmitter output stage.
Regulator loops having temperature compensated diode detectors of this type are used e.g. in connection with radio telephones, where the output signal from the power amplifier (PA stage) is monitored to ensure correct transmission power. Temperature compensated detectors are frequently used for this purpose, as the response of the detector will otherwise vary with the temperature. This is particularly so with portable radio telephones, as these are frequently carried in environments of great temperature fluctuations, without the telephone being expected to respond to this.
U.S. Pat. No. 4,523,155 discloses a temperature compensated diode detector, where a detector diode is incorporated in a half-wave rectifier. The compensator diode has a double function, as it partly compensates for the temperature dependence of the detector diode, and partly forms part of a bias circuit, whereby the voltage on the detector diode input is raised to a value corresponding to the voltage drop across the detector diode when it is conductive. The voltage on the detector diode output corresponds to the RF signal when it is positive, and otherwise assumes the value zero.